The present invention relates to a central controller for receiving, handling and transmitting messages to a plurality of selective call receivers.
Currently, manufactured central controllers, henceforth referred to as paging terminals, transmit messages on a number of paging transmission protocols. These protocols include the Golay, POCSAG, 5/6 tone, and the two-tone signalling protocols, as well as several others. The operation of these protocols are well known to those familiar with the art. Paging terminals generally receive messages and determine the proper protocol for transmission of each message and then transmits the messages to the selective call receivers. Selective cal receivers include paging devices and henceforth are referred to as pagers.
A number of methods are used in order to receive, handle and transmit the messages to the pagers by the paging terminal. A first method for handling the transmission of the messages is to transmit the messages in the order they are received. Because of the synchronization phenomenon associated with some of the signalling systems, substantial delays are required between the transmission of some protocols. The delays between the transmission of these protocols tends to reduce the overall throughput of the paging terminal, thereby reducing the amount of messages information that can be transmitted on a channel, thus reducing the channel loading.
Other paging terminals accumulate messages into their respective protocols prior to transmission, and then transmit the messages of each protocol. In accumulating messages in this manner, a protocol can be transmitted without interruptions between the messages, thereby reducing the delay between the transmission of messages. Additionally, some protocols, such as Golay and POCSAG, require a preamble be transmitted prior to message transmission. By accumulating messages within their respective protocols, the transmission of preamble signals can be substantially reduced. Paging terminals operating in this manner may use a sequential order for transmitting message protocols. For example, first a Golay protocol will be transmitted followed by a POCSAG protocol and followed by a 5/6 tone protocol and then followed by a two-tone sequential protocol, wherein the terminal then returning back to the first Golay protocol to transmit messages accumulated during the transmission of the other protocols.
An improvement upon this technique has been to accumulate messages within a protocol until a predetermined message size within the protocol is obtained. When the size is obtained, the messages protocol is transmitted. This technique has a disadvantage in that messages may be held for substantially long time waiting for the message protocol to reach a certain size prior to transmission. This sort of message delay is undesirable in the operation of a paging terminal. Consequently, some terminals transmit message protocols even if they have not reached a predetermined size if the message is within the protocol are of a certain age. However, transmission of a protocol before an optimal size is reached decreases the paging terminal's throughput. In order to improve the throughput of the paging terminal, it would be advantageous to provide a means for adjusting the maximum age of a protocol prior to transmission, the maximum age adjustment being based upon the channel loading characteristics.
Additionally, paging terminals receive messages of a certain maximum size, wherein the message is received, handled and transmitted by the paging terminal when it is less than or equal to the maximum size. In order to improve the throughput of the paging terminal, it would be advantageous to provide a means for adjusting the maximum size of the message received by the paging terminal based upon the channel loading characteristics.
Furthermore, paging terminals hold all messages of a protocol to a constant maximum size. It is desirable for some pager users to receive messages larger than the constant maximum size. For this kind of message service, some pager users would be willing to pay a premium. Alternately, some pager users wish to economize on the message service payment and would accept messages smaller than the constant maximum size. Thus, it would be desirable to establish a means for individually determining maximum message size of a message according to each pager user. It would also be desirable to adjust this individual maximum message size based upon the channel loading characteristics.
Additionally, the tariff structure of paging messaging is typically a fixed monthly price independent of the time of day in which a message is transmitted. Thus there is no motivation for users of a paging service to defer messaging to hours of the day where the system were not so heavily loaded. Thus it would be advantageous to provide a billing means which varies the tariff charge for messaging on the basis of the time of the day, wherein the time of day corresponds to system loading.
Channel loading characteristics are predictable based upon the time of day. FIG. 1 shows a prior art illustration of the system loading or channel loading of a typical paging transmission channel. Given these characteristics, it would be desirable to provide a means for adjusting the maximum size of an incoming message by the time of day. Also, it would be desirable to provide adjustment of the maximum size of the messages accumulated within a protocol buffer by the time of day in order to optimize the system throughput. Furthermore, it is desirable to optimize the maximum age of messages accumulated within the protocol buffer by the time of day in order to balance the throughput with the message delay.
An indication of the channel loading also can be found by determining the total message held within the paging terminal. It would also be desirable to increase the throughput of the paging terminal by adjusting the input message size, the maximum size and the maximum age of messages accumulated within a protocol, based upon the total messages held within the paging terminal. Finally, it would be desirable to increase the throughput by adjusting these same parameters as a combination of the total messages within the paging terminal and the time of day.